Type metal transportation system



April 25, 1961 w. J. TRABILCY 2,981,818

TYPE METAL TRANSPORTATION SYSTEM Filed Dec. 17, 1958 4 Sheets-Sheet lApril 25, 1961 Filed Dec. 17, 1958 W. J. TRABILCY TYPE METALTRANSPORTATION SYSTEM 4 Sheets-Sheet 2 W MW ATTORNEYS April 25, 1961 4Sheets-Sheet 3 Filed Dec. 17, 1958 l l l l 1 l l l I l l I I I l I l l 1i l I I l l |IJ m /m/ w nwfi f g m w r firm m 1 u w "w b ATTORNEYS April25, 1961 w. J. TRABILCY 2,981,818

TYPE METAL TRANSPORTATION SYSTEM Filed Dec. 17, 1958 A I ,?26 V 4Sheets-Sheet 4 652 8 Z; a 3m ;?86 898 r a? ifif 306 am 5.: y. 5

K ER 68 INVENTOR #44144; mam/m ATTORNEY5 United States Patent TYPE METALTRANSPORTATION SYSTEM William J. Trabilcy, Englewood, N.J., assignor toElectric Pipe Line, Incorporated, Jersey City, N.J., a corporation ofNew Jersey Filed Dec. 17, 1958, Ser. No. 780,974

13 Claims. (til. 219-19) This invention relates to a heating andtransportation system for distributing a fluid and is more particularlyconcerned with a system for the transportation of a fluid through a pipeline which is heated by an electrical current passing th rethrough.

One possible application of the present invention is in connection withthe distribution of type-metal utilized by newsprinting industries inthe production of cast printing plates for rotary printing presses. Thistype-metal generally is composed of 85% lead and 15% antimony and has amixture melting temperature of approximately 525 F. The type-metalusually is melted down in large capacity melting pots capable ofhandling to 70 tons of metal and is pumped therefrom to casting stationswhere new plates are cast for use in a printing run. After the platesare cast, they are delivered to the pressroom and are Imounted on theprinting presses for the press run.

At the end of the press run, it has been the customary practice to storethe used or dead plates until type-metal is again required for castingnew plates. Thus, as the demand for new plates arises, the dead platesare removed from storage and melted down in the melting pots.Consequently, it will be appreciated that the handling of the castingmaterial has a direct influence on the operating costs and productivecapacity of the printing plant. The present invention is presentlyconcerned with the handling of casting materials in such an operation toenable more efilcient systems to be utilized in the melting and castingof the printing plates.

Inithe past it has been customary to locate the casting stations in theimmediate area of the melting pots so as to reduce the distance overwhich the moltenmetal must be conveyed. In this manner, the difficultiesencountered in delivering metal in molten state at requiredunchilledcasting temperature are overcome to some degree. Also, the possibilityof the molten metal becoming solidified due to exposure to normal roomtemperatures before it can be introduced into the casting mold issubstantially obviated.

While this type of a system overcomes some of the serious problemsrelating to the physical handling and transportation of the moltenmetal, it presents other and more serious difliculties relating to plantlayout, handling of the cast plates eflicient utilization of plant floorspace and interdepartmental coordination, in addition to the usuallyencountered problem of preventing the molten metal from being chilledwhich results in defects and surface imperfections in the final castproduct.

The plant layout problems arise primarily because of the space requiredto locate the casting stations close to the melting pots, andthetransportation of dead plates to and from a storage area which isusually remote from the press and casting rooms. Thus, substantial costsare involved in the handling, re-handling and storage of the castplatesduring movement between the press room, storage and casting areas.Coordination of the individual departments in the intermittent handlingof the .cast

I 2,981,818 Patented Apr. 25, 1961 ice plates becomes inflexible, oftenresulting in bottlenecks and inefiicient utilization of labor. As aconsequence it has been found to be highly desirable in the promotion ofover-all plant efliciency and economy to locate the casting stationssubstantially remote from the melting pot. In some instances Where alarge bulk of printing plates is used, it is desirable to provide for acentral pot reservoir system to feed a series of smaller melting potswhich are connected to the molds of the casting station. With this typeof central feeding system, the used or dead plates are transferred fromthe press room to the central heating reservoir immediately after thepress run. There, the dead platesrare continually melted down and thetemperature of the molten metal is thermostatically maintained at theproper casting temperature. The central reservoir is of adequatecapacity to eliminate the necessity of storing the dead plates andfurther provides adequate molten metal to meet peak demands for newcastings. However, due to the size and weight of such a central heatingreservoir, it is necessarily located remote from the casting stations onthe ground floor or in the basement of the plant. Similarly, Where thegeneral location of the printing plate casting stations is not limitedby factors involving the handling of the molten type metal, maximum useof plant facilities, space and arrangement of equipment is obtainable toprovide for optimum efiiciency and economy. In the past, however, nooperable transportation system of commercial value has been devised toeffect the efficient, dependable and speedy handling of the molten metalbetween two widely separated points to allow for the casting stations tobe remotely located from the melting pot or to permit the employment ofa central reservoir heating system.

When electricity became commercially available with the recognition ofthe numerous advantages offered by heating with an electrical current,several attempts were made to economically transport the type-metal inits molten state from the melting pot to the remote casting station inorder to facilitate a more efficient and less costly plant layout. 'Someof these attempts involved the heating of the pipe line used forconveying the molten type metal with external resistance heatingelements generally of the electrical wrap-around cable or rodheatertypes. It also has been proposed in the past, to heat the pipe line bypassing electrical current through the walls of the pipe line itself.Such prior systems and apparatus, however, have not been found to becommercially satisfactory to keep the type-metal in its molten stateduring transportation from the'melting pot to the remote castingstations.

rial being transported in a flowable state involves thebasic problem ofconfining the electrical circuit to the pipe line, particularly whilethe metal is being poured from the pipe line into the casting box. Ingeneral, these prior proposed systems fail to show how the electricalcurrent can be specifically limited to flow through :desired straightand curved sections of pipe without grounding and with consequent properbalance and -uniform distribution of current throughout the. pipe linecircuit. v

It has been suggested that the particular problem of grounding of theelectrical current which occurs through the discharging stream of moltenmetal could be overcome by shutting down the heating system while themolten metal is being poured This proposal, however, results inineflicient heating and additional time-consuming operations in additionto the possibility of having the metal solidify within the pipe whilethe pouring operation is being consummated. Moreover, these priorsystems in attempting to confine the current path to the pipe lineitself in order to achieve a commercially useful system, have developedundependable, complicated apparatus leading to inordinate initialexpense and troublesome maintenance requiring the services of skilledand expensive maintenance personnel. Thus, these systems have been foundto be totally unsuitable for normal commercial and industrial use. i

Another serious problem with the proposed prior systems which utilizethe pipe line wall as the electric heating unit, is the large capacityrequired to heat a metal to maintain it in a liquid state. This problemis magnified by the influence of the required high operatingtemperatures upon the electrical resistance of the current-carrying pipeline. It will be appreciated,- with respect hereto, that the electricalresistance of a conduit increases substantially in direct proportion totemperature increases. This significant increase in the resistance ofthe circuit due to increasing conduit temperature has been previouslyovercome by initially providing equipment of adequate capacity to handleboth the heating of the material and to provide for sufficient power toovercome the resistance offered by the conduit at the elevated operatingtemperature. Thus, the transformer size employed to develop the requiredlow voltage-high current power for heating the pipe is consequentlyproportionately heavier thereby increasing the cost and over-allphysical size of the unit. As a consequence, it will be appreciated fromthe foregoing, that the systems which have been proposed areconsequently costly and operatively uneconomic for commercial uses, thusprecluding the plant designer from availing himself of the moreefiicient and less costly disposition of the metal casting stations orother stations of usage at a location which is substantially remote fromthe melting furnace or pot.

the present invention further contemplates the utilization of the novelheating and transporting system hereinafter described generally inheating and transporting any fluid capable of being heated andtransported through a pipe line. For example, the principles of thepresent invention may be applied with respect to heating and trans-.fluid is conveyed through a pipe line which is heated by passing acontrolled electrical current therethrough. This is accomplished inaccordance With the present invention by connecting the pipe line to beheated to the secondary winding of a transformer to establish a specialload circuit and connecting diiferent pre-selected numbers of primarycoil turns across a voltage source in circuit interrupting sequence bymeans of a novel control circuit so that the voltage induced in' theload circuit is capable of being controlled relative to the voltageacross the primary coil. The-control circuit for controlling thevoltagein duced in the transformer secondary winding is responsiveappended claims and the annexed drawings wherein:

to variations in the electrical resistance of the pipe line elfected bychanges in pipe line temperature and functions to re-establish andrestore a selected power input to the pipe line, which is lost when thepipe line electrical resistance increases with a rise in pipe linetemperature, which increase in resistance effectuates a fall in themagnitude of current flowing in the secondary load circuit.

Accordingly, it is a further object of the present invention to providea novel heating and transporting system wherein a pipeline is heated bypassing an electrical current therethrough and wherein increases inelectrical circuit resistance eflected by increases in pipe linetemperature is compensated for by controlling the voltage induced intothe electrical circuit which includes the pipe line.

A further object of the present invention is to provide in a novelheating and transporting system wherein a pipe line is heated by passingan electrical current therethrough by means of a transformer, a novelcontrol circuit for controlling the voltage induced into the secondarywinding of the transformer relative to the voltage across the primarywinding of the transformer in response to predetermined variations ofpipe line electrical resistance elfectuated by variation in pipe linetemperature.

Still a further object of the present invention is to provide in a novelheating and transporting system wherein a pipe line is heated by passingan electrical current therethrough by means of a transformer having itssecondary winding connected to.the pipe line, a novel control circuitfor selecting different predetermined num' bers of transformer primaryturns to be connected across a voltage source in circuit interruptingsequence, which control circuit includes time delay means for providinga predetermined period of time in which the secondary winding of thetransformer cannot be energized following de-energization thereof topermit the current in the secondary winding to collapse completelybefore inducing a further voltage therein.

Still another object of the present invention is to provide in a novelheating and transporting system wherein ated apparatus utilizing thefluid heated and transported by the pipe line.

A further object of the present invention is to provide a novel heatingand transporting system for the efficient, dependable and speedyhandling of a fluid through a pipe line which is heated by passing anelectrical current therethrough in a safe and eflicient manner tomaintain the fluld therein in a heated and flowable condition.

Further objects of the present invention will presently appear as thedescription proceeds in connection with the Figure 1 is a top plan viewof a heating and transportatron system embodying the principles of thepresent invention according to a preferred embodiment thereof andschematically illustrating the system controls;

Figure 2 is a left end elevation of the system of Figure l as indicatedby line 22 in Figure l;

Figure 3 is a side elevation of the system of Figure l as indicated byline 33 in Figure 1 and illustrating the metal melting pot in section;

Figure 4 is a section substantially along line 4-4 of Figure 1illustrating the pipe hangers and insulation; 7

Figure 5 is a schematic view illustrating the secondary electrical loadcircuit of the system of Figure 1;

Figure 6 illustrates the schematic wiring diagram for a control systemfor the system of Figure l;

' Figure 7 is a side elevation view of a transportation system accordingto a further preferred embodiment of the invention illustrating themelting and reservoir pots storing the'molten melt in section;

Figure 8 is a schematic view illustrating the secondary load circuit of.the system of Figure 7; and r Figure 9 is an enlarged view of. theinsulating flange illustrated in Figure 2.

Referring now to the drawings and more particularly to Figures 1-4wherein the construction embodying the principles of the invention areshown, reference numeral 20 generally designates a hot-lead system suchas that utilized in newsprinting plants for producing the plates inprinting newspapers. This system 20 comprises a typemetal plate meltingpot 22 whichis mounted on the floor by suitable structural forms 23 anda casting box 24 enclosing a metal shell mold for forming the type-metalplates. This melting pot is heated by any suitable means (not shown) toapproximately a temperature of 700.F.

for melting the type-metal and to maintain the metal in a molten state.

To deliver the metal in its molten state at an unchilled temperaturetothe casting box 24, a pipe line 26 is provided and comprises a supplybranch 28 and a. return branch 30. These branches 28 and 30 are suitablyinterconnected .at their corresponding casting box ends by a three-wayplug type valve 32 which isarr'anged to be positioned over the pouringspout of the casting. plate mold. At the melting pot end of the pipeline'26, the supply branch 28 terminates below the normally'maintainedlevel of molten metal as indicated at 34 in a pump intake housing 36.This housing 36 contains a suitable pump impeller (not shown) which isconnected to an upstanding pump shaft 38. Shaft 38 is coupled at 40 to asuitable motor 42 or other suitable prime mover which is mounted onsuitable structural forms generally indicated at 44 over the melting pot22. The return branch 30 is spaced apart from the supply branch 28 andterminates over the melting pot and near the level of the molten metalas indicated at 45.

' The supply and return branches 28 and 39 are illustrated to besubstantially in parallel spaced-apart relation and are substantially ofthe same linear length for a purpose as will hereinafter becomeapparent. All of the pipes and fittings are preferably made of steel oriron ha ving threaded, fiangedor welded joints in accordance with thetemperature and pressure of the service. The pipes are covered with asuitable thermal and electrical insulation material 46 over which acanvas jacket 48 is sewn. Suitable hangers 50 are provided to supporteach branch 28 and 30 individually from the building, by suitable hangerrods 52 connected thereto. Rods 52 are electrically insulated from thepipes by providing a union 54 composed of electrically insulatingmaterial which will not conduct electrical current. The insulation andpipe support hangers have been omitted from all the .figures with theexception of Figure 4 for'olarity.

Both the supply and returnpipe branches 28 and 30 are anchored to thebuilding against undue movement by electrically insulated anchors 256which are individual. to each branch near the correspondingends'thereof. Each of the anchors 56cor'nprises a' nipple-or shortlength of pipe 58 welded or otherwise-suitably secured to-its associatedbranch at one end and is coupled at its other end to arigidly securedanchor pipe 60 by an insulating coup1ing62 whichserves to electricallyinsulate-the anchor pipe 60 from the pipe line 26. Thecoupling 62 asshown in Figure 9 comprises a flange 64 secured to the end of pipe 60anda flange 66 secured to thea'djacent end of pipe branches.

Under actual working conditions, the melting pot end of the supplybranch 28 is immersed and consequently electrically grounded in themolten metal stored in the melting pot 22, which metal provides anelectrical path through the metal Walls of the melting pot, thestructural support 23 to earth. It further will be appreciated that whenthe plug valve 32 is opened to pour molten metal into the casting box24, another electrical ground will be established since the dischargingmetal will provide an electrical path to interconnect the pipe line 26with the casting box. Moreover, the pipe line may be permanentlyelectrically connected to the casting box 24 by a shrouding (not shown)which is employed to shield against the splashing and splattering ofmolten metal as it. enters the casting box. Consequently, the particularelectrical circuit established between the transformer secpipe 581 byscrew threads, welding or other suitable means. a

An insulating annulus 68 and bolt 70 insulated from the flange securethe coupling together. Any other structurewhich electrically insulatesthe two flanges of the coupling may :be alternativelyused in'place of.the struc ture' shown. L v I In order to pass a'ciirrent through thepipe -line;26 for heating and raising' theteniperature ofthepipe line;26 to liberate heat to; the molten metal therein, atransformer 801sprovided having' avariable tap primary winding 82 ondary winding 84andthe pipe line 26 will be the determining factor in whether ornotcontinuity between the above two grounds will be established.

It will be appreciated that when continuity between the pipe linegrounds is established through the casting apparatus in conforming theheating system to actual working conditions, that there \m'll be a flowof current through the melting pot and casting box apparatus. Thiscondition, it will be appreciated, is extremely hazardous in that theoperators in handling the casting apparatus are subject to severeelectrical shock, the magnitude of which is dependent upon the voltageinduced in. the pipe line and other surrounding conditions such as wetor damp floors. Also where continuity between pipe line grounds isestablished, electrical sparks will be produced as the molten metal isdischarged, from the valve 32 and strikes the casting, box 24. r

. Inaccordance with the present invention the above hazards areeliminated without necessitating any change or alteration in Workingconditions or the process of producing the final castings. This isaccomplished by electrically connecting the separated correspondingmelting pot ends of the supply and return branches 28 and 30 togetherwith a jumper Wire 98 or other suitable means to establish and completea continuous or looped load circuit 100. This load circuit 100 may betraced from the supply branch 28, through the plug valve 32, the returnbranch 30, the jumper 98 and back to the supply branch 28. Referring toFigure 5, the circuit 100 is provided with two positive electricalgrounds 101 and 101a to earth so that the electrical impedances betweenthe grounds are equal. Where the supply and return branches 28 and 30are substantially of equal length, the ground 101 is connected .to theplug valve 32 or to the pipe line 26 sub} stantially in the region ofthe plug valve. This ground 161 may also be established by electricallyconnectingthe plug valve 32 to the castingbox 24. The other ground 101ais connected to the end of the supply branch 28 which is immersed in themolten metal stored in the melting pot 22 or other vparts of the pipeline 26 immerscd in the molten metal such as the pump housing 36. Asbest shown in FigureS, the secondary winding terminal. clipv lugs 94 and96 are connected respectively to the supplyand return branches 28 and 30at the electrical impedance midpoints between the grounds. 101, and101a. Consequently, the-elect1ical impedances in the continuous loadcircuit-100 between groundlOl andsecondary termi- :terminals of theprimary winding 82 are connected across :asource of voltage 102, thepotential induced across the terminals of 'the'secondary winding 84causes substan- ;tially equal magnitudes of current to flow through twoparallel circuits of substantially equal impedance. The first of thesecircuits includes conductor 90 connected to terminal 86 of secondarywinding 84, the portion 104 of .the supply branch 28, the plug valve 32,the portion 106 'of the return branch 30 and conductor 92 which isconnected'to the other terminal 88 of the secondary winding.

The other circuit initiates from the terminal 86 of the secondarywinding 84, and passes through conductor 90, through the portion 1080fsupply branch 28, through jumper 98 which connects the correspondingmelting pot ends of the supply andreturn branches; through the portion110 of return branch 30 to conductor92 which connects withthe otherterminal 88 of the secondary wind- }pg L Therefore, in theabove-described parallel circuit paths of equal impedance, there isnocontinuity between the grounds 101 and 101a and consequently there is nocurrent flow through the casting and melting potapparatus. -Theoperation of the making the castings is carried on in the same manner asbefore the application of the molten metal heating and transportingsystem embodying the principles of the present invention. Operators mayhandle the melting and casting apparatus without experiencing electricalshock and no electrical sparks are produced by the pouring of the moltenmetal into the casting box 24 since the pipe line is eifectivelyelectrically isolated from the casting box 24 and the melting pot 22'to' confine the flow of current to the load circuit 100.

Since the current flowing throughout the pipe line 26 isfequal, it willbe appreciated that the pipe line will be heated uniformly; Thisadvantage eliminates the development of hot and cold sections of thepipe line and assures uniform heating of the molten metal therein.

"Referring now to Figure 6, and in accordance with the presentinvention, a control system 120; is provided in a suitable control panel122 to automatically maintain the pipe line temperature within anoperating predetermined range and to utilize substantially fulltransformer'capacity throughout the entire temperature range of heating.Thus, with continued reference to Figure 6, the voltage source 102 isconnected across the primary winding 82 of transformer 80 to establish apower circuit which includes a three-position relay type selector switch124. This relay type selector switch 124 includes two switch blades 126and '128. Blade 126 is engageable with a pair of contacts 130 and 131and blade 128 is engageable with the pair of contacts 132 and 133. Theseblades 126 and 128 are operated by armatures 134 and 136 which aremechanically interlocked by linkage 138 which prevents the switch blades126 and 128 from engaging their respective sets'of contacts at the sametime and furtherprovides for the breaking of one set of contacts beforethe other set can be made. This is accomplished byproviding for anarm,140' which is centrally pivoted at 142. Pivotally connected toopposed ends of the arm 140 are links 144 and146 one on each side of thepivot at 142. These links 144- and 146 respectively are connected to thearmatures 134 and 136. The pivot arm 140 isbiased'by means notshownto aneutral contact disengaging position by a clockwise rotation whichdisengages the blades 1 26 and 128 from their respective contacts.

' Inaddition to the mechanical interlock, a conventional electricalinterlock (not shown) may also be provided to preventboth switch blades126'and 128 from completing their associated circuits at the same time.;The relaytype selector -switch-124 also includes separ'atelyenergiz'edarmature windings 148 and 149 which operate armatures 134 and-136respectivelyto alternately move switch blades-126 and 128 intoengagement Withiathil' associated-sets of contacts. fContacts 13.1;and

1133are contacted in series circuit relation 'with an ammeter'156 tothepower source conductor 158.

: 'Thegcontacts 130. and 132 respectively are arranged in terminal 164'and the taps and 162'respectively,

which :terminal 164 isconnected directly to power source conductor 166.Thus, energization of winding 148 makes contacts 130 and 131 toarrangethe maximum number of primary turns N across thevoltage source 102 whilealternate energization ofwinding 149 makes contacts 132 and 133 toarrangea smaller preselected number of primary turns N across thevoltage source. It will be appreciated that this variance in the numberof primary turns across the voltage source will raise and lower thevoltage induced in the secondary Winding in inverse pro portion to thenumber of turns across the primary voltage source.

In order to automatically control -the three-position switch124, aconventional thermostat 168 is provided which includes a bulb 170suitably strapped to the supply branch 28 to sense the pipe linetemperature, and a capillary tube 172 interconnecting the bulb 170 witha bellows 174. -The bellows 174 is connected by linkage 175 to a movableswitch blade 176 of two-position switch 178 which is included in thecontrol circuit 120-. 'The bulb, capillary tube and bellows are filledwith' gas so that the bellows responds to' the pressure of the gas whichin turn is'responsive to the pipe line temperature. Thus the switchblade 176 is movable upon rise or fall in the temperature of the pipeline 26 and. is biased by means not shown to engage contact 180. Upon apreselected temperature rise in the pipe line 26, the blade 176 is movedby expansion of the bgllows to engage contact 182. Upon a preselectedfall in pipe line temperature the blade 176 'disengages from co ct 182and moves into engagement with contact 180 Engagement of the switchblade 176 with contact 180 energizes relay 184. Engagement of the'switchblade with contact 182 alternatively energizes relay 186. Both relays184and 186 are of the type having a long pull-in time and may be one ofseveral conventional relays having the'characteristic of slow make andfast break. For example, relays 184 and 186 may be of the type h'avingadash pot or a slugged core to provide the long pull-intim'e. I

The relay 184 includes a winding 188, a movable switch blade 190 andstationary contacts 192 and; 194. This relay 1-84' is shown to be inde-energized condition wherein. the movable switch blade 190 is biased,by means not shown, to ,be out of engagement with contacts 192 and'194.Upon energization of relay 184 the-switch blade 190" movesinto-engagement with the stationary contacts 192 and 194 after apreselected time delay.

2' Similarly, the relay 186 is shown to be in de-energized condition andincludes a winding 196, a movable switch blade 198 and stationarycontac'ts 200 and 202. The switch blade- 198 is biasedby means not shownto be out of" engagement with contacts 200 and 202. Upon energization ofrelay 186, switch blade 198 moves into engagement with the stationarycontacts 200 and 202 after a preselected time delay." V ;Since contacts192 and 194 are in series relationship with winding 148 ofthethree-position switch 124 across tion iwith'these contacts isenergized toac tivatethe three temperature thermostat having athermostatic bulb 206 strapped to the supply branch 28 to sense thetemperature of pipe line 26 and a capillary tube 208 which interconnectsthe bulb with a bellows 210. The bellows 210 is connected by linkage 212to a movable switch blade 214 of switch 216 which is included in thecontrol circuit 120. The bulb 206, capillary tube 208 and bellows 210are filled with gas so that the bellows responds to the pressure of thegas which in turn is responsive to the pipe line temperature similar tothermost'at 168. This thermostat 204 indicates the need for heat tomaintain the pipe line 26 at a preselected operating temperature and isoperable upon a preselected fall and rise in pipe line temperature tomove the switch blade 214 into and out of engagement respectively withan associated switch contact 218 of switch 216. Energized by actuationof thermostat 204 is relay 184 or 186 depending upon the position ofswitch blade 176 of the two-position switch 178.

Also included in the electrical network are indicator lamps 220, 222,224 and 226. The indicator light 220 is connected across the voltagesource to indicate application of voltage across the power sourceconductors 158 and 166. Indicator light 222 which is in series circuitrelation with contact 227 of switch 216 indicates the de-energization ofthe control circuit by thermostat 204 when the demand for heat issatisfied and switch blade 214 is in engagement with contact 227;Indicator light 224'serves to indicate that relay 186 is energized whileindicator light 226 serves to indicate that relay 184 is energized.

- 'The apparatus of the present invention is shown in the standbyde-ener'gized condition wherein the pipe line 26 is at ambient roomtemperature and the voltage source 102 is disconnected from the controlcircuit 120 and the transformer 80 byline switch 228. The thermostat V204, for purpose of this embodiment, moves the blade 214 into and out ofengagement with contact 218 at 600 F. and 700 F. respectively, thistemperature range being the operating range for the system in order tomaintain molten type metal in a flowable and unchilled state.Consequently, in the standby condition, switch blade 214 is inengagement with contact 218 indicating the need for operation of thetrans-former. At temperatures up to 325 E, switch blade 176 of switch178 is in engagement contact 180, the force exerted by bellows 174 notbeing sufficient to overcome the bias against blade 176. Since none ofthe relay windings are energized, the three-position switch 124 isbiased to its neutral circuit disengaging position as shown.

To set the system in operation for heating the pipe line 190 will bemoved into engagement with contacts. 192 and 194 after a predeterminedtime delay. This completes an energizing circuit to winding 148 of thethreeposition switch mechanism 124 which is in series "circuit timeindicator light 226 which is in parallel circuit relation withwinding'1-88 is illuminated. When relay 184 becomes energized, theswitch blade 10 relation with contacts 192 and 194 across the powerinput "conductors 158 and 166.

When winding 148 is energized, the switch blade 126 will move intoengagement with contacts 130 and 131 to complete an energizing circuitto the transformer primary winding 82 to energize the maximumpredetermined number of turns N in the primary winding. This circuit tothe primary winding 82 may be traced from the power input conductor 166,through conductor 240 which electrically interconnects input conductor#166 with the primary winding terminal 164, through the turns'N ofprimary winding 82 to tap 160, through conductor 242 to contact 130,through switch blade 126 and contact 131, through conductor 244connected to contact 131 and through the ammeter 156 to the other powerinput conductor 158. w When current-flows through N turns in the primarywinding 82, a corresponding voltage is induced in the secondary winding84 of transformer to cause current to flow through the pipe line 26 inthe load circuit to uniformly heat the pipe line as hereinbeforedescribed. As the temperature of the pipe line gradually increases froman initial ambient temperature it will be appreciated that theresistance of the metal of which the pipe line is composed will increaseappreciably with temperature. Consequently, the magnitude of electriccurrent and therefore the transformer power (1 R) delivered to the loadcircuit 100 will fall as the temperature of the pipe line is increasedfrom an ambient temperature which is generally 70 F. to the normalmaximum operating temperature of 700 F. for keeping the molten typemetal of the present embodiment in a flowable and un chilled state.

In accordance with the present invention, the initial electric currentpassed through the pipe line and the corresponding transformer power (PRor VI for the transformer secondary) for initially preheating the pipeline from ambient temperature are the rated current and rated outputrespectively. e As the temperature increases with a correspondingincrease in electrical resistance to cause the current to fall todecrease the heat input into the pipe line, thermostat 168 responds to aselectedtemperature of the pipe line 26 to operate switch 178 and moveswitch blade 176 out of engagement with contact 182. This temperaturefor operating switch 178 is, in accordance with the present embodiment,selected in the preheating temperature range of the pipe lineintermediate the ambient and operating pipe line temperatures and ispreferably 325 F. to provide a final operating electrical current ofadequate magnitude to properly heat 'themolten metal.

Disengagernent of the switch blade 176 with contact 180, ie-energizesrelay 184 to disconnect the relayblade 190 from contacts 192 and 194 tothereby de-energize winding 148 which in turn disconnects switch blade126 from contacts and 131 to allow the switch 124 to assume a neutralcircuit de-energizing position. This action interrupts the energizingcircuit for the transformer primary coil 82 to de-energize the primarycoil.

Upon disengagement of contact the switch blade '176 is moved to connectwith contact 182. This com- .pletes an energizing circuit to winding1960f time delay re'lay 186 which is connected across the contact 182and power conductor 166. At the same time, indicator light 224 which isin parallel circuit relationship with winding 1% is illuminated. Whenrelay 186 becomes energized,

v experienced.

gize a preselected number of turns N in the winding which is less thanthe maximum number N The mechanical interlock 138 hereinbefore describedfunctions to insure disconnection of contacts 130 and 131 when .thearmature 136 moves switch blade 128 into engagement with contacts 132and 133.

The circuit now made through the selected coil portion N of the primarywinding -82 may be traced from the .power input conductor 166 throughthe conductor 240 which electrically interconnects input conductor 166with the primary winding terminal 164, through the turns N of theprimary winding 82 to tap 162, through conductor 250 to contact 132,through the switch blade 128 to contact 133, through conductor 244connected to contact 133 and through the ammeter 156 to the other powerinput conductor 158.

Consequently, the voltage impressed across the secondary winding 84 byenergization of N turns in the primary coil 82, will be greater than thevoltage impressed by energization of the N turns of the primary windingby a magnitude which is in direct proportion to the fraction of N /Ncoils. This increase in impressed secondary voltage restores acorresponding magnitude of electric current in the load circuit 100,which current has been steadily dropping due to the increase in circuitresistance caused by the temperature rise of the pipe line.Consequently, a corresponding power input to the pipe line is alsorestored so as to reestablish the heat input into the pipe line to raisethe temperature thereof to the operating range and to provide foradequate liberation of heat to the molten metal when the metal is passed.through the pipe line to keep it flowable. and in an unchilled state.

The magnitude of power delivered to the pipe line which is restored, ispreferably the rated value of the transformer so as to facilitatemaximum usage of the equipment. Thus, as the temperature of the pipeline 26 is increased with its corresponding increase in electricalresistance and the load circuit current with its corresponding power (1R) falls with a resulting drop in heat input to the pipe line, thecontrol circuit 120 functions to restore and re-establish the rated kva.of the transformer. This particular feature of the present inventioneliminates the necessity of providing for a larger conventionaltransformer wherein poweroutputs cannot be selectively varied to meetoperational requirements. Consequently, substantial savings in initialcost of equipment are achieved in addition to the advantage ofpermitting the utilization of equipment which is of smaller size andmore easily handled. The efficiency of the transformer also is increasedsince substantially maximum rated power outputs are facilitatedthroughout the range of temperatures towhich the pipe line is subjected.

Although the primary winding 82 is shown and described to have two setsof alternately selectable coil turns N and N the present inventionfurther contemplates the utilization of the novel control circuitdescribed herein to accommodate as many sets of coil turns as requiredto accomplish a particular operation. Thus, the primary winding 82 maybe provided with additional taps between the terminal 164 and the taps162 and 160 as required. For each additional tap provided for, anadditional circuit energizing switch in the relay type switch mechanism124 is required in addition to a time delay relay for actuating theadditional switch.

The purpose of providing for the long pull in time of relays 184 and 186is to allow for a complete collapse of current in the transformersecondary whenever the primary winding 82 is de-energized so that whenthe primary winding'is re-energized, no current bucking is It will beappreciated in this respect that when the terriperature of the pipe line26 reaches its intermediate value of 325 F. and thermostat 168 functionsto cause the operation of theswitching mechanism 124 tode-ener- '12gizethe turns of coils N in the primary winding 82 and to energize theturns N in circuit interrupting sequence,

that -as soon as the switch blade 176 breaks from contact 180, themagnetizing current and therefore the magneticflux begins to collapse.Since the current collapse is not instantaneous due to a closedsecondary circuit, the

irate of flux drop increases the rate of cutting conductors of thetransformer winding to induce a high pressure voltage into the primarywinding 82. If line voltage is impressed across the primary at the timethat the secondary is injecting this electrical pressure, the phenomenongenerally referred to as bucking will occur.

The severity of the phenomenon referred to above is dependent upon thepoint of the pressure wave at which switching in occurs and results inarcing at the switch contacts and chattering of switch contacts whichultimately leads to considerable damage to the relays and switchingmechanisms. Such arcing and chattering further produces trains of highfrequency waves which impinge upon the transformer windings andvrepresent a distinct menace to the insulation to ultimately causedielectric breakdowns.

With the present invention, it will be appreciated that the problem ofbucking resulting from the switching in and out of the transformer iseliminated since in switching from primary coil turns N to N in currentinterrupting sequence, the relay 186 provides an adequate time delayperiod before contacts 200 and 202 are made by switch blade 198 toenergize winding 149 which in turn completes the energizing circuit tothe. coils N Alternatively, under certain conditions where the pipe linetemperature drops due to, for example, excessive flow. of materialthrough the pipe line, the thermostat functions to move the switch blade176 out ofengagement with contact 182 and into engagement with contact180. This re-establishes. the initial preheat circuit for energizingtime delay relay 188 which facilitates the energization of primary coilsN Consequently, the relay 188 with its long pull in time does not permitthe energization .of coils N for a predetermined time period to allowfor a complete collapse in the current in coils N Either relays 186 or188 will function to prevent bucking whenever the disconnect switch'228is rapidly switched in and out in the same manner as described above.

When the temperature of the pipe line reaches a preselected maximumwhich is approximately 700 F. in the present embodiment, the thermostat204 functions to move the s'witchblade 214 of switch out of engagementwith contact 218 and'into engagement with contact 227. This interruptsthe transformer energizing by de-energizing relay 186 which in turnde-energizes winding 149 to cause the three-way switching mechanism 124to assume its neutral de-energized. position thereby de-energizing theprimary coil 82. Connection of the switch blade 214 to contact 227illuminates the indicator light 222 to indicate 2 that need for heat issatisfied. I

When the'temperature drops to a pre-selected value, whichis 600-F. .inthe present embodiment, the'thermostat functions to move the switchblade 214 back into engagement with contact 218 to facilitatere-energization of primary coil turns N as hereinbeforedescribed.

In place ofthe thermostat 168, which measures the pipe line temperatureand consequently indicates the relaon the ground floor of the printing.plant and'a plurality of remote spaced-apart melting pots 22 (only oneshown) as hereinbefore'de'scribedi In the embodiment illustrated in.Figure. the melting pots 22 now servetomaintafn 13 the molten metaldelivered thereto in a flowable and unprinting room (not shown) andabove the central melting I reservoir 262.

The central reservoir and melting pot 262 is heated by any suitablemeans (not shown) to approximately a tem perature of 700 for meltingdown the type metal plate 264 as they are removed from'the printingpress (not shown) following a printing run. The dead plates are placedon any suitable and conventional conveyor 266 upon their removal fromthe press and are transferred directly to the melting reservoir 262 tobe melted down. To deliver the type metal in its molten state to eachreservoir melting pot 22, a pipe line 268 is provided and comprises atleast a supply pipe 270. At the central reservoir end of the pipe line268 the supply ipe 270 terminates below the level of the molten metal asindicated at 272 in a pump intake housing 274. This housing 274 containsa suitable pump impeller (not shown) whichis connected to an upstandingpump shaft 276. Shaft 276 is coupled by any suitable means to aconventional electric motor 278 or other suitable prime mover which ismounted on structural forms generally indicated at 280 over thereservoir 262.

As hereinbefore described, the pipes and fittings of pipe line 268 arepreferably and conventionally made of steel or iron having threaded,flanged or welded joints in accordance with the temperature and pressureof the service. I The pipe line is suitably covered with a thermal andelectrical insulation material (not shown) and the hanger rods (notshown) for supporting the pipe line are the same as those illustrated inFigure 4.

A float level control ot shown) operates motor 278 to deliver moltemetal to the pot 22 when the level of the molten metal therein falls toa preselected level bv withdrawal of molten metal therefrom for deliveryas required to the casting boxes 24 (see Figure 1). This may beaccomplished in the present embodiment in accordance with the embodimentillustrated in Figure 1. Where it is not required to s ace the castingboxes 24 from the pot 22, the casting box 24 may be loc ted im---mediately adjacent to the pots 22 in aconventional manher with acommunicating passage therebet'ween for conveying the molten metal fromthe pot to the casting box With continued reference to Figure 7, thecontrol circuit 120 and transformer 80 shown therein is 's'ihst tiallyidentical with that shown in Figures 1- a d described in connectiontherewith. With the exception or 284 and 286 which terminate inconventional cliplugs' 288 and 290. These clip lugs 288 and 290 arepreferably a 'welded to the ends of pipe 270 to assure good electricalconnections. The other terminal 88 ofthe secondary winding 84, isconnected to the electrical impedanoe midpoint of the pipe 270 by asuitable conductor'296 which sirnilarly terminates in a lug clip 298,which lug'clip is also preferably welded to the pipe. The endsof thepipe 270 are immersed in the molten metal to provide electrical groundsto earth. The pipe 270 also is positively grounded to earth byelectrical grounds 300 and 3M 'whe'ref the conductors 284 and 286 areconnected to the pipe to assure zero potential at these points.

consequently; two parallel electrical circuits having an equalelectrical impedance are provided throughthe pipe 270. The first ofthese circuits may be traced from terminals 86, through the conductor284, through-the portion'306 ofpipe 270, and through conductor 29% tothe other secondary winding terminal "88.. The other parallel circuitmaybetraced from secondary winding 'terminal 86"th'rough electricalconductor 286,7thfo'11gh the portion 308 of the pipe 270, and throughthe-conductor 290 to the other terminal 88 of the secondary winding 84.

Therefore, in the above-described parallel circuit paths of equalimpedances, there is no continuity between the grounds 306 and 308 andconsequently there will be no current flow through these grounds and theassociated melting and reservoir pots 22 and 262. Thus, with thisembodiment wherein current is passed through the single pipe 270to heatthe latter so as to liberate heat to the molten metal flowingtherethrough, the operation of making castings is carried on in the samemanner as before the application of th'e'molten metal heating andtransporting system embodying the principles of the present inventionand the same result is achieved as with the embodiment of Figures 1-6.Operators may therefore hand'le all of the melting, casting apparatuswithout experiencing electrical shock since the pipe line 268 iseffectively electrically isolated from the melting and reservoir pots'22 and 26Zso as to confine the flow of current to the load circuit 282.

Since-the current flowing throughout the pipe line 268 is equal it willbe appreciated that the pipe line will be heated uniformly. Thisadvantage as hereinbefore described eliminates the development of hotand cold sections in the pipe line and insures a uniform heating of themolten metal therein.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore in- .CJClBd to be embracedtherein. i I

7 What is claimed and desired to be secured by United States LettersPatent is: a

1. In a system for use in heating and transporting a fluid between twospaced-apart stations, a supply pipe line having an electricalresistance which increases as 'its temperature increases and adapted tointerconnect said stations for conveying the fluid therethrough,electrical heating means for raising the temperature of said pipe lineby passing an electrical current therethrough to heat the fluid thereincomprising a transformer capable of supplying a plurality of differentsecondary voltages and including a primary winding and a secondaryWinding, s id secondary Winding having two terminals connected 1: saidpipe line to establish a load circuit, a source of input-voltagearranged to be connected across said primary winding to establish apower circuit, selecting means for connecting different predeterminednumbers of primary turns to be connected across said source insequencewhereby the voltage induced in said load circuit is controlled relativeto the voltage across saidprimary winding, and control circuit means foroperating said selecting means to decrease the number of primary turnsacross said source in response to a predetermined increase in theelectrical resistance of said pipe line effected by the temperature riseto increase the voltage in the secondary winding and to approximatelyre-establish and restore initial power input to said pipe line.

2. The system as defined in claim 1 wherein said control means includestime delay means for rendering said selecting means inoperative toconnect said primary windingacross said source for a predeterminedperiod of time following de-en'ergization of said primary winding toprovide for a substantially complete collapse of current in said loadcircuit before said primary winding is reenergized. a

j 3+ The. system as defined in claim 1 wherein said selecting meanscomprises switching means having at least 15 ranged in said powercircuit to be associated with difierent predetermined numbers of turnson said primary winding.

4. The system as defined in claim 3 wherein said control circuit meanscomprises a thermostatically operated two-position switch having amovable contact responsive to the temperature of said pipe line, firstand second control circuit relay means having switch contacts andindividual energizing circuits connected in energizing circuitrelationship to said two-position switch to be energized in sequence bysaid movable contact, said first and second relay means each having timedelay means providing a long pull-in time for closing said switchcontacts on said relay means, switch actuating means individual to eachof said circuit making positions of said switching means and arranged incircuit energizing relationship with each of said time delay relay meansswitch contacts for selectively actuating said switching means from saidneutral position to complete said power circuit associated with saidcircuit making positions and energize said primary winding apredetermined selected time period after associated ones of said firstand second relay means are energized.

5 The system as defined in claim 4 wherein said control circuit meansincludes a thermostatically operated switch responsive to thetemperature of the material being conveyed through said pipe line tode-energize said first and second relay means irrespective of theposition of said two-position switch, and means for biasing saidthree-position switching means to said neutral position when said relaymeans are de-energized thereby de-energizing said primary winding at apredetermined temperature of the material.

6. In a system for transporting an electrically conductive fluid betweena supply station and a receiver station,

a pipe line interconnecting said supply station with said receiverstation including a supply branch for withdrawing fluid from said supplystation and terminating in fluid discharge means at said receiverstation and a recirculating return branch substantially equal in lengthto said supply branch and connected to said discharge means forrecirculating undispensed fluid back to said supply station, meanselectrically connecting together said supply and return branches attheir corresponding ends to establish' a continuous circuit ofelectrical resistance, means electrically grounding said continuouscircuit at two separate spaced apart points near said supply station andsaid receiver station respectively to provide substantially equalelectrical impedances between said points in either direction along saidcircuit, electrical means for passing an electric-a1 current throughsaid pipe line to heat the fluid therein comprising a transformer havinga primary winding and a secondary winding, said secondary winding havingtwo terminals respectively connected to said continuous circuit atspaced-apart points providing substantially equal electrical impedancesbetween said terminals and adjacent electrical grounding means in saidcontinuous circuit whereby flow of electrical current is confined tosaid continuous circuit and said secondary Winding to electricallyisolate said pipe line from said stations irrespective of flow ofelectrically conductive fluid therebetween. V

7. The system as defined in claim 6 wherein pumping means are providedto circulate said fluid through said pipe line under pressure.

8. In a system for use in heating and transporting a fluid, betweenspaced-apart supply and receiving stations, a supply pipe line having anelectrical resistance which --perature of'said pipe line from an ambienttemperature to an elevated operating temperature comprising meanselectrically connected to said pipe;line to.,.f9rr,n a llQad;

circuit, selector means for inducing different selected substantiallyconstant voltages in said load circuit to effectuate current flowtherein and means responsive to a predetermined drop in magnitude ofcurrent flow in said load circuit as eflectuated by the rise intemperature of said pipe line for controlling said selector means toincrease the voltage induced in said load'circuit by a selectedmagnitude and thereby re-establish and restore approximately the initialmagnitude of power input to said pipe line to increase the current flowin said load circuit.

9. Ina system for use in heating and transporting a fluid betweenspaced-apart supply and receiver stations, a supply pipe line having anelectrical resistance which varies directly with the temperature thereofand adapted to interconnect said stations for conveying said fluidtherethrough, electrical power supply means for passing an electricalcurrent through said pipe line to heat and raise the temperature of saidpipe line comprising a transformer having a primary winding and asecondary winding, said secondary winding having at least two terminalsconnected to said pipe line to establish a load circuit, said primarywinding having at least three spacedapart taps and a preselected numberof coil turns between said taps, a source of input voltage arranged tobe connected to a selected pair of said taps to establish a powercircuit, selecting means for changing the taps connected to said sourcein circuit interrupting sequence whereby the number of primary coilturns connected across said source is varied by a preselected magnitude7 to control the voltage in said load circuit and the power variesdirectly with the temperature thereof and adapted applied to said pipeline relative to the voltage across said primary winding and controlmeans responsive to a predetermined increase in the pipe line electricalresistance eflFectuated by the rise in temperature of said pipe line forautomatically operating said selecting means to decrease the number ofprimary turns across said source by a preselected magnitude toapproximately re-establish the initial power input across the pipe.

10. The system as defined in claim 9 wherein said control means includestiming delay means to render said selecting means inoperative toenergize said primary windingrfor a predetermined time period followingdeenergization of said primary winding to provide a complete collapse ofthe current in said load circuit prior to re-energization of saidprimary winding.

11. The system as defined in claim 10 wherein said selecting meanscomprises three-position switchng means having at least two separatecircuit making positions and a neutral circuit de-energizing positionbetween said circuit making positions, each of said circuit makingpositions being arranged in said power circuit to be associated wit-hsaid diflerent predetermined numbers of primary turns in series circuitrelation across said source, said timing delay means being electricallyinterconnected with said switching-means to render said switching meansinoperative in said neutral circuit'de-energizing position.

-12. In a system for use in transporting a fluid between separatedstations of usage, a pipe line interconnecting said stations forconveying said fluid therebetween and having an electrical resistancewhich varies directly with the temperature thereof, electrical means forpassing an electrical current throughrsaid pipe line to heat and raisethe temperature of said pipe line comprising a transformer having aprimary winding and a secondary winding, said secondary winding havingtwo terminals connected to said pipe line to establish a load circuit,.a

- source of input voltage arranged to be connected across said primarywinding to establish a power circuitand means included in said powercircuit for selecting different predetermined numbers of primary turnsto be connected across said source in circuit interrupting sequencewhereby the voltage in said load circuit and the power input thereto iscontrolled relative to the voltage across said primary. windingcomprising three-position switching means having at least two separatecircuit making positions and a neutral circuit de-energizing positionbetween said circuit making positions, each of said circuit makingpositions being arranged in said power circuit to be associated with oneof said different predetermined numbers of primary turns in seriescircuit re lation across said source, control circuit means forautomatically operating said three-position switch to de-' crease thenumber of primary turns in response to a predetermined increase in theelectrical resistance of said pipe line efi'ectuated by the rise intemperature of said pipe line to re-establish a selected power output ofsaid transformer and time delay means for rendering said three-positionswitching means inoperative in said neutral position so that saidprimary winding remains deenergized for a predetermined time delayfollowing each de-energization of said primary winding to provide for asubstantially complete collapse of current in said load circuit beforesaid primary winding is re-energized.

18 13. In the system defined in claim 12 wherein said fluid iselectrically conductive and said pipe line is electrioally connected tosaid stations and wherein said load circuit includes means for confiningthe flow of current through said pipe line and said secondary Winding toelectrically isolate said pipe line from said stations.

References Cited in the file of this patent UNITED STATES PATENTS743,331 Ries Nov. 3, 1903 1,338,408 Thornton Apr. 27, 1920 1,733,250Davis Oct. 29, 1929 1,917,205 Horle July 4, 1933 1,994,838 Swoboda eta1. Mar. 19, 1935 2,306,831 Proctor Dec. 29, 1942 2,602,916 AndersonJuly 8, 1952 2,707,313 McShurley et a1. May 3, 1955 UNITED STATES PATENTOFR/ICE CERTIFICATE OF CORRECTION Patent No. 2,981,818 April 25 1961William J. Trabilcy It is hereby certified that error appears in theabove numbered patent requiring correction and that the said LettersPatent. should read as corrected below.

Column 5 line 37, for "39" read' 30 column 16, line 39, after "pipe"insert line line 47, for 'swltchng read switching Signed and sealed this26th day of September 1961,

' (SEAL) Attest:

ERNEST w. SWIDER DAVID L. LADD Attesting Officer I Commissioner ofPatents USCOMM-DC- UNITED STATES PATENT OPE/ICE CERTIFICATE OFCORRECTION "Patent No. 2,981,818 Ap 2 1961 William J. Trabilcy It ishereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent. should read ascorrected below.

Column 5 line 37, for "-39-"- read 30 column 16 line 39, after pipeinsert line line 47, for sw1tchng"- read switching Signed and sealedthis26th day of September 1961,

' SEAL) At test:

Attesting Officer Commissioner of Patents USCOMM-DC"

